Integrated ambient sensing devices and methods of manufacture

Abstract

An ambient sensing device is described especially suited to the sensing of a variety of ambient parameters. Photolithographic techniques are used to pattern a multiplicity of sensitive layers on a single monolithic substrate taking into account the wide range of plastic, gelatinous and ceramic materials to be patterned and the problems of their cross-contamination when in contact.

What is claimed is: 
     
       1. A multi-element ambient sensing probe comprising: a semiconductive substrate,   a plurality of transistor devices defined by photolithographic techniques in said semiconductive substrate, each said transistor device including a control electrode,   a first means for sensing at least one property of the ambient, said first means comprising a first sensitive material defined by photolithographic techniques on said substrate and in electrical connection with a first said control electrode, and   a second means for sensing at least one property of the ambient different from that sensed by said first means, said second means comprising a second sensitive material defined by photolithographic techniques on said substrate and in electrical connection with a second said control electrode, wherein at least one of the first and second sensitive materials would dissolve the other if they came in contact.   
     
     
       2. The apparatus of claim 1 wherein the first sensing means is connected to said first control electrode by a first conductor formed on an insulating layer on said semiconductor substrate. 
     
     
       3. The apparatus of claim 2 wherein the first conductor comprises a signal line and a conductive shield. 
     
     
       4. The apparatus of claim 1 wherein the first and second transistor devices are field effect transistors and the control electrodes are gate electrodes. 
     
     
       5. The apparatus of claim 1 wherein the first and second transistor devices are bipolar transistors. 
     
     
       6. The apparatus of claim 1 wherein the first and second sensing means and the plurality of transistor devices are all formed on the same side of the semiconductive substrate. 
     
     
       7. The apparatus of claim 3 wherein the signal line and shield are formed photolithographically. 
     
     
       8. The apparatus of claim 7 wherein the signal line and shield are formed of polysilicon.